Study On The Characterization Of Actinomycete Strain 200-09 And Antifungal Constituents In Its Cultured Broth

This research was about an antifungal actinomycete strain 200-09,isolated from a soil sample collected from the coast of Hawaii,USA.The strain was identified to be the species Streptomyces antibioticus on the basis of its cultural characteristics,morphological characteristics,physiological and biochemical characteristics and 16 S rDNA sequence analysis.We found that strain 200-09 possessed high similarity to Streptomyces antibioticus and Streptomyces griseoruber by 16 S rDNA sequence analysis.Then we compared the cultural characteristics,morphological characteristics and physiological and biochemical characteristics of strain 200-09 with above two species,we found that 200-09 was more similar to Streptomyces antibioticus.Thus it was identified to be a strain of Streptomyces antibioticus.Based on its antifungal activity,we selected the best medium for its fermentation to get secondary metabolites enough for research by large-scale fermentation.We studied the antifungal fractions of 200-09 based on the antifungal activity guided experiment.By applying various chromatographic(silica gel,Sephadex LH-20 and ODS column chromatography and preparative HPLC,et al.),twenty-two compounds were obtained from the cultured broth of strain 200-09.They were identified by spectroscopic methods(NMR,HR-MS,UV,IR,et al.)as antimycin A1a(1)and A1b(2),antimycin A2b(3),antimycin A3a(4)and A3b(5),antimycin A7b(6),antimycin A10a(7)and A10b(8),antimycin A15(9),antimycin A16(10),kitamycin A(11),kitamycin B(12),kitamycin C(13),urauchimycin B(14),deisovaleryblastomycin(15),streptomyceamide C(16),ergosta-7,22-diene-3?,5?,6?-triol(17),ergosta-7,22-diene-3?,5?,6?-triol(18),ergosterol peroxide(19),ergosterol(20),actinomycin D(21)and actinomycin X2(22),among which 13 was a new compound.The antifungal activities and cytotoxicities were evaluated for them.We found that antimycins showed good activity against Candida albicans and good cytotoxicities,and actinomycins displayed weak activity against Candida albicans,but significant cytotoxicities with an IC50 value of lower than 1.6 ?g/mL.